University of Kentucky UKnowledge Theses and Dissertations--Chemistry Chemistry 2015 UNHINDERED TRIANGULENE SALT PAIRS: SUBSTITUTION- DEPENDENT CONTACT ION PAIRING AND COMPLEX SOLVENT- SEPARATED DISCOTIC IONS IN SOLUTION Subrahmanyam Modekrutti University of Kentucky, [email protected] Right click to open a feedback form in a new tab to let us know how this document benefits ou.y Recommended Citation Modekrutti, Subrahmanyam, "UNHINDERED TRIANGULENE SALT PAIRS: SUBSTITUTION-DEPENDENT CONTACT ION PAIRING AND COMPLEX SOLVENT-SEPARATED DISCOTIC IONS IN SOLUTION" (2015). Theses and Dissertations--Chemistry. 50. https://uknowledge.uky.edu/chemistry_etds/50 This Doctoral Dissertation is brought to you for free and open access by the Chemistry at UKnowledge. It has been accepted for inclusion in Theses and Dissertations--Chemistry by an authorized administrator of UKnowledge. For more information, please contact [email protected]. STUDENT AGREEMENT: I represent that my thesis or dissertation and abstract are my original work. Proper attribution has been given to all outside sources. I understand that I am solely responsible for obtaining any needed copyright permissions. I have obtained needed written permission statement(s) from the owner(s) of each third-party copyrighted matter to be included in my work, allowing electronic distribution (if such use is not permitted by the fair use doctrine) which will be submitted to UKnowledge as Additional File. I hereby grant to The University of Kentucky and its agents the irrevocable, non-exclusive, and royalty-free license to archive and make accessible my work in whole or in part in all forms of media, now or hereafter known. I agree that the document mentioned above may be made available immediately for worldwide access unless an embargo applies. I retain all other ownership rights to the copyright of my work. I also retain the right to use in future works (such as articles or books) all or part of my work. I understand that I am free to register the copyright to my work. REVIEW, APPROVAL AND ACCEPTANCE The document mentioned above has been reviewed and accepted by the student’s advisor, on behalf of the advisory committee, and by the Director of Graduate Studies (DGS), on behalf of the program; we verify that this is the final, approved version of the student’s thesis including all changes required by the advisory committee. The undersigned agree to abide by the statements above. Subrahmanyam Modekrutti, Student Dr. Arthur Cammers, Major Professor Dr. Dong-Sheng Yang, Director of Graduate Studies UNHINDERED TRIANGULENE SALT PAIRS: SUBSTITUTION-DEPENDENT CONTACT ION PAIRING AND COMPLEX SOLVENT-SEPARATED DISCOTIC IONS IN SOLUTION DISSERTATION A dissertation submitted in partial fulfillment of the requirement for the degree of Doctor of Philosophy in the College of Arts and Science at the University of Kentucky By Subrahmanyam Modekrutti Lexington, Kentucky Director: Dr. Arthur Cammers, Professor of Chemistry Lexington, Kentucky 2015 Copyright © Subrahmanyam Modekrutti 2015 ABSTRACT OF DISSERTATION UNHINDERED TRIANGULENE SALT PAIRS: SUBSTITUTION-DEPENDENT CONTACT ION PAIRING AND COMPLEX SOLVENT-SEPARATED DISCOTIC IONS IN SOLUTION This work sought to enforce aromatic interactions between compatible -molecular orbital systems with ionic bonding. In this case the interacting partners are oppositely charged discotic triangulene derivatives. The observed properties of the heterodimeric ion-pairs likely arise due to a hypothetical synergy between electrostatics and - interactions. The work presented here describes investigation of putative covalency arising from this hypothetical synergy in the electrostatics driven -stacking. In order to probe this, various hypotheses were made and experiments were designed to test their validity. The results from the experiments show existence of contact ion-pairs and complex solvent-separated discotic ions in solution. The formation of complex ion-pairs arise due to the fact that the electrostatic interaction that brings the discotic ions together is strong, but does not neutralize when the contact is made. So, the dipole created by the monopoles in a dimeric contact ion-pair can attract ions at both termini forming oligomers. This process apparently continues towards highly aggregated states and then to nanometric species and at some point the material precipitates. The propensity to aggregate and form complex-ions limited our approach to the measurement of the energetics of the ion-pairing for two reasons: (1) the observables had a complex dependence on temperature, solvent, concentration and ionic strength; and (2) the mass in solution was undergoing kinetic evolution towards solid states. The turbidimetric effects arising due to aggregate formation further complicated the extraction of weak interactions between the ions and hence effects determination of ion-pairing constants. Keywords: triangulenes, pancake bonding, -stacking, ion-pairing Subrahmanyam Modekrutti 05/04/2015 UNHINDERED TRIANGULENE SALT PAIRS: SUBSTITUTION-DEPENDENT CONTACT ION PAIRING AND COMPLEX SOLVENT-SEPARATED DISCOTIC IONS IN SOLUTION By Subrahmanyam Modekrutti Dr. Arthur Cammers Director of Dissertation Dr. Dong-Sheng Yang Director of Graduate Studies 05/04/2015 Date To my family... ACKNOWLEDGEMENTS I deem it my honor to write this section of the document, as the work presented here would not have been possible without individual contributions from various people… At the outset, I would like to thank my advisor, Dr. Arthur Cammers, who has put in a lot of effort in various capacities, scientific or otherwise, to transform the immature individual in me into a student of science. His constant guidance during my graduate career has helped me to improve my thinking critically and scientifically. I remember my first meeting with him when he encouraged me to think ‘beyond’- this is still in progress.. I would like to thank my committee members, Dr. Mark Meier, Dr. Tonglei Li and Dr. Edith Glazer, for taking out time to critically comment, suggest and encourage me to think deeper, during the interactions I had with them. I would like to thank Dr. Peter Spielmann, who as an external examiner during my defense, provided useful insights to look at my work with another perspective. I would like to thank Dr. Susan Odom, who very generously allowed me to use the UV- Vis spectrophotometer and the potentiostat in her laboratory to carry out most of the analysis presented in this work. I would also like to thank the postdocs in Odom group, Dr. Aman Preet Kaur and Dr. Selin Ergun, for helping me with electrochemical measurements. I would like to thank Dr. Sean Parkin for running X-ray diffraction analysis on my samples. I would like to thank Mr. John Layton for helping me with NMR studies. I would like to thank Department of Chemistry and University of Kentucky for allowing me to use their facilities. I would like to thank my group members, Pramod, Sheldon and Allen, who were helpful with scientific discussions in the lab alongwith maintaining healthy work environment. The interactions with other graduate students in the department were also fun and productive and contribution from other people of the department is inseparable. iii I would like to thank my friends in Lexington (long list). In their company I got to learn many things and also spent moments of fun that I will cherish throughout my life. I would like to express heartfelt acknowledgements to my best friend, Aman, for standing by me and encouraging me all the time. I would like to thank my mother and father who have showered their love unconditionally and gave me the strength to move forward. I wish to thank my brother, sister, brother-in- law and sister-in-law and their kids for their love and affection. I can only hope to become the one they loved the most. I would like to thank my relatives for thinking and praying for me. In all humility, I would like to express my deep sense of gratitude to the Almighty, for being my side, then and forever… iv Table of Contents ACKNOWLEDGEMENTS ............................................................................................... iii Table of Contents ................................................................................................................ v List of Figures .................................................................................................................. viii List of Schemes ................................................................................................................... x List of Tables ..................................................................................................................... xi Chapter 1 ............................................................................................................................. 1 1.1 Aim of the Work ........................................................................................................... 1 Reader’s guide: ................................................................................................................... 1 1.2 Background ................................................................................................................... 2 1.3 Pancake Bonding .......................................................................................................... 5 1.4 Is there any covalency in electrostatic driven -stacking? ........................................... 8 1.5 Molecular Orbital Calculations ..................................................................................